Systemic Carnitine Deficiency (SCD) is a human genetic disease inherited through autosomal recessive inheritance, the main symptoms being skeletal or cardiac muscle disorders (NIM 212140) (Roe, C. R. and Coates, P. M., Mitochondrial fatty acid oxidation disorder, The metabolic and molecular bases of inherited diseases 7th ed., edited by Scriver, C. R., Beaudet, A. L., Sly, W. S. and Valle, D., McGraw-Hill, New York, 1995, 1508-1509; Karpati, G. et al., The syndrome of systemic carnitine deficiency: clinical, morphologic, biochemical, and pathophysiologic features, Neurology 1975, 25:16-24). Serum carnitine levels and intra-tissue carnitine levels are known to be extremely low in these patients compared to healthy individuals. Carnitine is an indispensable co-factor in the long-chain fatty acid metabolism. A carnitine-mediated mechanism enables intracellular fatty acids to permeate mitochondrial outer and inner membranes, and energy is produced when these fatty acids undergo β-oxidation within the mitochondria (Walter, J. H., L-Carnitine, Arch Dis Child, 1996, 74:475-478; Bremer, J., Carnitine metabolism and functions, Physiol Rev, 1983, 1420-1480). The abnormal decrease of carnitine concentration in systemic carnitine deficiency patients is thought to be the direct cause of diseases in tissues such as muscles that require a large amount of energy. Membrane physiological studies done using fibroblasts from systemic carnitine deficiency patients have shown that these cells lack the mechanism to transport carnitine from the outside of the cell to the inside. A gene that encodes a protein involved in this mechanism is presumed to be the gene responsible for this disease (Tein, I. et al., Impaired skin fibroblast carnitine uptake in primary systemic carnitine deficiency manifested by childhood carnitine-responsive cardiomyopathy, Pediatr Res, 1990, 28:247-255). However, the gene responsible for systemic carnitine deficiency is yet to be isolated.